Activated packs must first be boiled (and the crystals melted), and then activated again for instant heat (or for cool, place in the refrigerator only). Please check out "789tens Reusable Instant Heat Instructions" below for details.
After your activated heat pack cools down, it will begin to solidify. In order to reuse the pack it must be boiled in water to turn the contents back into a liquid. Depending on the size of the pack, this process normally takes between 5 to 25 minutes.
Instructions for boiling your heat pack:
1. Use a nonstick pot to boil the water. If you do not have a nonstick pot, then wrap your pack in a towel before boiling it in the pot. If the pot is not large enough to accommodate your hardened pack as-is, then fold it into thirds (or as necessary) before wrapping or placing it in the pot.
2. Fill the pot with enough water to fully submerge your pack, and bring the water to a boil. You may add the boiling water from a kettle in order to speed up the boiling process.
3. Safely place your pack in the pot. You can do this either before or as the water boils.
4. Boil your pack for at least 5-30 minutes (this does not include the time it takes for the water to heat up to a boil). Ensuring that 100% of the crystals have melted is necessary. Smaller packs should take 5-10 minutes, larger packs 15-25 minutes to melt all the crystals.
5. Turn the heat off before removing your pack from the pot. Place it on a clean and safe surface, and allow it to cool down to a safe temperature. If your pack was wrapped, then unwrap it before laying it to cool.
6. Now you can activate your pack for instant heat, or place it in the fridge to use as a cold pack. Do not place your pack in the freezer, and it is not microwaveable.